Wearable sweat nicotine biosensor based on a nicotineoxidoreductase and its natural electron acceptor

Abstract

The advent of wearable biosensors is empowering clinical and lifestyle decision making. Nicotine is a drug of significant negative impact on public health given the prevalence of smoking and vaping. Yet noninvasive, continuous monitoring of nicotine is challenging due to lack of specific and sensitive biosensing elements. Here, we report a wearable highly sensitive nicotine biosensor and demonstrate on-body deployment of the sensor in a first-in-human study. The biosensor comprises nicotine oxidoreductase (NicA2) with its natural cytochrome c electron acceptor (CycN) as mediator: both proteins play a key role in the nicotine-degrading bacterium, Pseudomonas putida S16. The biosensor detects nicotine over four-orders of magnitude (0.1-100 M) with nanomolar sensitivity (LOD [~]33.6 nM), performs in the physiological pH range (pH 6-9), and is highly selective against common interferants and the major human nicotine metabolite, cotinine. Incorporation of the biosensor in a custom wearable device enables real-time measurement of nicotine from locally induced sweat on volunteer subjects and demonstrates higher analytical accuracy than gold-standard mass spectrometry.